Production of aromatics and dehydrogenated hydrocarbons



PRODUCTION OF AROMATICS AND DEHYDROGENATED HYDROCARBONS Filed Dec. 11 1953 PUR/FIEQ bun r/cs IND 05 EN 5 70 N 8 0 fillllu. 6C 7 N 00 2 w um R I T 00 8 64 yr m 4 Mn 5 w m vm D o 6 I y 15 2 \I 2 4 ME 7 z 2 UN 0 02 Z 0 v 7 5 6 m l K I v-I r. ln/II M IIHIIIO C IIII 0 IHHH P 4, w R 4 HI 0 4 w. 6 0 v m y m I H m up u H M; A

Tl FRY HES/DUE IN V EN TOR. J6 mes A. Anderson, Jz,

A TTORNEY United States Patent 2 PRlSDUCTION 0F AROMATICS DEHYDRO- GENATED HYDROCARBONS James ArAnderson, Jr., Baytown, Tex., assignor, by mesne Assignments, to Esso Research and Engineering Company, Elizabeth, N. J., a corporation of Delaware Application December 11, 1953, Serial No. 397,732 V 6 Claims. (Cl. 260-668) The present invention is directed to a method for obtaining .aromatic hydrocarbons. More particularly,

vtlle invention is "directed to a method for purifying aromatic hydrocarbon fractions. In its more specific 'aspects, theinvention is directed to a method for purifying aromatic hydrocarbons and forming valuable hydrocarbons, suchas styrene and indene and their alkylated I homologues, *hereinafter; referred ,to as styrenes and indenes. a i ,-The present invention may be briefly, described as a method for obtaining aromatic hydrocarbons in which a feed aromatic hydrocarbon fraction containing saturated hydrocarbons and alkylated aromatic hydrocarbons and indaues and boiling in the, range between 100 and 550F. is subjected to a temperature between l100 and 1200" F.. in the presence of hydrogen in an amount in the range of 500 to 2000 cubic feet per barrel of feed stock to form a product containing an appreciated amount of aromatic hydrocarbons and dehydrogenated hydrocarbons, such as styrenesand indenes. The product is rapidly cooled or quenched to a temperature not in excess of 200 Fqand the quenched product is then distilled under a reduced pressu're at a temperature not in excess of 200 to rerrrove hydrocarbons boiling aboveand below the boiling range of the feed. The distilled product may then be inhibited with asuitable oxidation inhibitor to prevent undesirablereactions' of the hydrocarbons on storage.

1 The temperatures to be employed in the practice of the present invention suitably'are: in the range between 1100 andjl200' F. At adernperature below 1100" F. the aromatichydrocarbonsarenot purified and at temperatures above 1200 Rdealkylation reactions become undesirably extensivei "A preferred temperature is about II SO ZF. W i

I --':Pressures-m'ay suitably range from 0 to-300 pounds per square inch gauge with desirable resultsobtained at about 1-50 poundsper'square-inch gauge; g

The heating operation maybe conducted for ati m e in the. range from '1 to 50 seconds with-quite desirable results being obtained when a temperature of about1150" F. is used at about 7*se'conds. t f 1 The reacting. surface in the reaction zone may be either .a ceramic surface or it may be analloyof steelsu'ch as one of thechrome-nickel types of the 18'8 or 25-20 type For the lower alloys, such as 18-8 stainless-steel,

. "formation of metallic carbide. Sulfur compounds are suitable, for producing this. effect.

feed stock may suit bly comprise aromatichydrocarbons containing an excess of about 40% by volume of aromatic hydrocarbons. This stock may contain alkylated aromatic hydrocarbons, such as toluene, xylenes, ethyl benzene, propyl'benzene, methylethyl benzene, .diethyl benzene and the like. The feed stock mayalso contain the indanes, such as 1;me thylindane; 2,methylindane; 4,methylindane; 5,methylindane; 4,5,6 -trimethylindane; Lhdimethylindane; 1,2-dimethylindane; 1,2,3-trimethylindane and 1,2,3,4,5,6,7,heptamethylindane. The aromatic hydrocarbon fraction may also contain olefins and saturated hydrocarbons, such ,as paraflins and naphthenes and compounds such as tetralin and its homologues. v

The aromatic hydrocarbon feed may suitablyboil in the range between about 100 and about 900 F. but preferably may boil in therange between about 100 and 550 F. While any aromatic hydrocarbon feed may be employed, the feed may suitably be a solvent extract of a kerosene fraction, such as a sulfur dioxide extract. The feed stock may also suitably be a heavy cracked naphtha, a gas oil, and the like, fractions thereof, orsolvent extracts of such fractions. .The feed stock may contain from about 40% to about aromatics and may be obtained from aromatic rich streams derived by solvent extraction of petroleum distillates or from fractions pro duced in catalytic conversion operations such as catalytic cracking. The aromatic feed may contain appreciable quantities of sulfur particularly when the aromatic fraction is a solvent extract of petroleum fractions such as sulfur dioxide extracts.

The quenching operation to reduce the temperature to a temperature not in excess of 200 F.may be conducted by contacting the product immediately after it leaves the heating zone with a hydrocarbon quenching liquid at a much lower temperature than the product. For example, a light fraction obtained by distilling the heated product may suitably be used asthe quenching liquid. It is desirable that the product be quenched to a temperature not in excess of 200 F. within about 30 seconds after the heating operation has been concluded to prevent polymerization of the product.

After the product has been suitably quenched it is then distilled at a reduced pressure at a temperature not in excess of 200 F. to avoid polymerization and to remove hydrocarbons boilingabove and below the boiling range hydrogenated hydrocarbons to products of higher boiling point whereby they may be removed from the purified aromatics and recovered for such use. The present invention will be further illustrated by reference to thedrawing in which the single figure represents a flow diagram of a preferred mode.

Referring now to the drawing, numeral 11 designates a charge line through which a feed stock of the type described is introduced into the system from a source, not shown. This feed stock may contain naphthenes or tetralines naturally occurring in the feed stock or naphthenes which may be added to the feed stock. The naphthenes may serve as a source of hydrogen and may replace part of the hydrogen in the operation. In'any event, the feed stock as described is introduced byline 11- and has admixed with it hydrogen introduced from a sourcenot shown by line 12 controlled by valvev 13. The mixture of aromatic feed and hydrogen is then introduced by line 11 into a hydrocracking zone 14 containing-a coil- "15' and which-is supplied with heat by burners 1 6; The temperature of the "mixture in coil-15- is' raised to a-"temperature within the range between 1100 and 1200 Frand themixture passed through thezone under thecontact-conditions mentioned hereinbefore. A prodnot is obtained Whichdischarges from zone 14 by line 17 into a quenching-zone 18- where the hydrocarbon product is rapidly cooled or quenched to a temperature not in excess of 200" F; by means of a hydrocarbon fraction introduced into zone 18- by line 19 from a source which will be described further. v

The quenched product from zone 18 is then discharged by line 20 into a distillation zone 21 which operates under a reduced pressure and which is provided with a heating means illustrated by a steam coil 22 and which is provided with suitable vapor-liquid internal contacting means, such as bell-cap trays, packing equipment and the like which are conventional to the art. Distillation zone 21 includes all auxiliary equipment normally associated with vacuum distillation operations and which will include means for inducing reflux, condensing and cooling means, evacuating means, and the like.

From distillation zone 21 there is recovered as overhead by line 23- gases and light fractions which are the products of cracking the paraffins and/or naphthenes included with the feed introduced by line 11. These products may be discharged from the system by line 23 for use as may be desired after removal of non-con densibles. A portion of these products is desirably employed as quench by introducing a portion of same by line 19'into'quenching zone 18. To this end, line 19 is provided with a valve 24 to control the amount of quench introduced into zone 18.

An aromatic fraction of appreciated aromatic content and containing d hydrogenated products, such as styrencs and indenes, and having substantially the same bq s Po nt an e a he rom c d i ec ver y line 25. Heavier ends are discharged from zone 21 by line 26 and these heavier ends may contain tarry residues which may result from polymerization of some of the product. The tarry residue and any heavy carbonaceous fraction produced in zone 14 and in zone 21 ll b of a m no a u The aromatic fraction in line 25 may be routed to storage or may be further treated as desired. It may be desirable to add to the aromatic fraction in line 25 aa zsidat c inh T hi d e ec nb tcd to line 25 aline 27 controlled by valve 23 which allows the introduction of an oxidation inhibitor intov the aro matic fraction to prevent undesirable reactions from takin Bl e bras pribr f r treatmen It may be seen from the foregoing description taken with the drawing that a number of features are associated with'my invention. The reaction takingplace in coil 15 is a hydrocracking operation in which substantially little, if any, coke is formed. In short, heavier products are not formed in the hydrocracking operation. The parafiins and naphthenes are removed from the aroma'tic hydrocarbons by conversion into lighter fractions, u h s. blsfi s- Th l la d roma s d he denes are not dealkylated but are dehydrogenated to form desirable styrenes and indenes. The tetralines are converted to naphthalene by a dehydrogenation reaction and may serve also. as hydrogen donors. Another desiraole feature of the present invention is that hydrogen is not consumed or made in the operation to any appreciable extent. Thus the hydrogen may be recycled to the operation, such as from line 23, if desired, after separation of the liquid. hydrocarbons therefrom. Still another desirable result obtained in the practice. of the present invention is the desulfurization of the aromatic rich feed stock by the reaction taking place in the reaction zone 14.

The present invention is particularly advantageous in producing from aromatic fractions of low aromatic content purified aromatic hydrocarbons having a purity greatly in excess of 90%.

In order to illustrate the invention further, a fraction boiling up to 445 F. obtained. from a sulfur dioxide extract of kerosene was subjected to a temperature in the range from 1100 to 1200 F. in the presence of 1155 standard cubic feet of hydrogen per barrel of feed. This fraction contained aromatics, alkylated aromatics, indenes, paraffins and naphthenes. The feed was charged to a oil t a a or blbc t of about bbt P r se and fora contact time of 6.73 seconds. The product obtained had a bromine number-0f 28.5 and contained 95.7% by volume of aromatics, 1% by volume of olefins and 3.3% by volume of saturates. The initial feed contained 74.4% by volume of aromatics.

Inanother operation a fraction boiling between-about 445 F. and 550 F. obtained from the same sulfur'dioxide extract of kerosene was passed through a heating coil at a temperature in the range between 1100 and 1150 F. at a hydrogen rate of 1147 standard cubic feet per barrel. The vapor velocity in this instance was 19.6 feed per second and the contact time was 7.12 seconds. The product had a bromine number of 29 and contained 99.6% by volume of aromatics, 0.2% by volume of olefins, and 0.2% by volume of saturates. In this instance, the feed stock had anaromatic content of 90.7% by volume.

In still another run the total liquid sulfur dioxide extract of kerosense boiling in the range from, 300 to 550 F and containing 82.2% byvolume of aromatics was heated to a temperature in the range from 1100 to 1150 F. in a coil in the presence of 1116 standard cubic feet of hydrogen per barrel. The vapor velocity .persecond was 20 feet and the contact time was about 7 seconds. Under these conditions the product obainedbad bromi e number 5 an an om c content of 97.1% by volume, olefins 0.6% by volume d. saturates 0.3%. y volume In e e e al. perations the bromine number is an indication of the presence of the dehydrogenatftdhydrocarbons, particularly the styrenes and indenes. It is to be noted that the product in each instance hasa, low content of olefins.

In. other operations, similar fractions were treatedat d fer nt temps ur r ample a .8. F- a fraction having an initial aromatic content of 74,4% was heated under similar conditions and the aromatic content was raised to 78.5% by volume indicating, that a temperature below 1100" F. does not give satisfactory results.

A gasoline fraction from a sulfur: dioxide extract of a kerosense fraction was subjected to. av temperature of 1150 E, a pressure of 150p. s. i. g. in thepresence. of 1000 cubic feet of hydrogen at contact times'of 3, 6, and 12 seconds to produce products having aromatic contents of 92%, 96%, and 100% aromatics. The feed stock-had an aromatic content of to per volumevof aromatics. In these runs the sulfur was reduced; from 0.95 weight percent. in the feed to levels of 0.3, 0.2, and 0.2 weight percent, respectively, forthe three products.

It is to be understood that a feature of my invention is the purification of aromatic hydrocarbons in the presence of hydrogen such that the saturated-hydrocarbons which are contained in the feed hydrocarbons are largely converted to products ofdifferent boiling points such that they may be removed by distillation. A feature of the invention is that this reaction in the presenee of hydrogen does not form coke and tarry bodies, In other words, the reaction coil 15 is not pluggedaft orig e tin m T rat h Sa QQ REQY bQHQ L l coillS, was opened after running at least 42 hours and it was found that the coil was free of clogging deposits. In numerous other runs of like duration, coking was not experienced.

The nature and objects of the present invention having been completely described and illustrated, What I desire to claim as new and useful and to secure by Letters Patent is:

1. A method for increasing the aromatic content of a feed stock containing aromatic and saturated hydrocarbons boiling in the range of about 100 to 900 F. which comprises the steps of heating said feed stock at a temperature of about 1100 to 1200 F. and a pressure of about to 300 p. s. i. gauge for about 1 to 50 seconds in the presence of hydrogen and in the substantial absence of any catalytic material to form a product containing an appreciated amount of aromatic hydrocarbons, cooling said product to a temperature of not more than about 200 F. within about 30 seconds, distilling said product to remove hydrocarbons boiling above and below the boiling range of said feed stock and recovering a distilled product containing said appreciated amount of aromatic hydrocarbons.

2. A method for increasing the aromatic content of a feed stock containing aromatic and saturated hydrocarbons boiling in the range of about 100 to 900 P. which comprises the steps of heating said feed stock at a temperature of about 1100 to 1200 F. and a pressure of above 0 to 300 p. s. i. gauge for about 1 to 50 sec onds in the presence of hydrogen and in the substantial absence of any catalytic material to form a product containing an appreciated amount of aromatic hydrocarbons, cooling said product to a temperature of not more than about 200 F. Within about 30 seconds, distilling said product at a temperature of not more than about 200 F. at a reduced pressure to remove hydrocarbons boiling above and below the boiling range of said feed stock and recovering a distilled product containing said appreciated amount of aromatic hydrocarbons.

3. A method for increasing the aromatic content of a feed stock containing aromatic and saturated hydrocarbons boiling in the range of about 100 to 900 F. which comprises the steps of heating said feed stock at a temperature of about 1100 to 1200 F. and a pressure of about 0 to 300 p. s. i. gauge for about 1 to 50 seconds in the presence of hydrogen in an amount in the range of about 500 to 2000 cubic feet per barrel of feed stock and in the substantial absence of any catalytic material to form a product containing an appreciated amount of aromatic hydrocarbons, cooling said product to a temperature of not more than about 200 F. within about 30 seconds, distilling said product at a temperature of not more than about 200 F. at a reduced pressure to remove hydrocarbons boiling above and below the boiling range of said feed stock and recovering a distilled product containing said appreciated amount of aromatic hydrocarbons.

4. A method for increasing the aromatic content of a feedstock containing aromatic and saturated hydrocarbons boiling in the range of about 100 to 550 F. which comprises the steps of heating said feedstock at a temperature of about 1100 to 1200 F. and a pressure of about 0 to 300 p. s. i. gauge for about i to 50 seconds in the presence of hydrogen in an amount in the range of about 500 to 2000 cubic feet per barrel of feed stock and in the substantial absence of any catalytic material to form a product containing an appreciated amount of aromatic hydrocarbons, cooling said product to a temperature of not more than about 200 F. within about 30 seconds, distilling said product at a temperature of not more than about 200 F. at a reduced pressure to remove hydrocarbons boiling above and below the boiling range of said feed stock and recovering a distilled product containing said appreciated amount of aromatic hydrocarbons.

5. A method for increasing the aromatic content of a feed stock containing aromatic and saturated hydrocarbons boiling in the range of about to 550 F. which comprises the steps of heating said feed stock at a temperature of about 1150 F. and a pressure of about p. s. i. gauge for about 1 to 50 seconds in the presence of hydrogen in an amount in the range of about 500 02000 cubic feet per barrel of feed stock and in the substantial absence of any catalytic material to form a product containing an appreciated amount of aromatic hydrocarbons, cooling said product to a temperature of not more than about 200 F. within about 30 seconds, distilling said product at a temperature of not more than about 200 F. at a reduced pressure to remove hydrocarbons boiling above and below the boiling range of said feed stock and recovering a distilled product containing said appreciated amount of aromatic hydrocarbons.

6. A method for increasing the aromatic content of a feed stock containing saturated hydrocarbons and at least 40% of aromatic hydrocarbons, said hydrocarbons boiling in the range of about 100 to 550 F., said method comprising the steps of heating said feed stock at a temperature of about 1150 F. and a pressure of about 150 p. s. i. gauge for about 1 to 50 seconds in the presence of hydrogen and in the substantial absence of any catalytic material to form a product containing an appreciated amount of aromatic hydrocarbons, cooling said product to a temperature of not more than about 200 F. within about 30 seconds and distilling said product at a temperature of not more than about 200 F. at a reduced pressure to remove hydrocarbons boiling above and below the boiling range of said feed stock and recovering a distilled product containing said appreciated amount of aromatic hydrocarbons.

References Cited in the file of this patent UNITED STATES PATENTS 1,441,341 Groves Jan. 9, 1923 2,184,234 Groll Dec. 19, 1939 2,381,522 Stewart Aug. 7, 1945 2,436,480 Mavity Feb. 24, 1948 FOREIGN PATENTS 1,058,136 France Nov. 4, 1953 OTHER REFERENCES Sachanen: Conversion of Petroleum, Reinhold Publishing Co., 'N. Y. (2nd ed., page 254 relied on), (1948). 

1. A METHOD FOR INCREASING THE AROMATIC CONTENT OF A FEED STOCK CONTAINING AROMATIC AND SATURATED HYDROCARBONS BOILING IN THE RANGE OF ABOUT 100 TO 900* F. WHICH COMPRISES THE STEPS OF HEATING SAID FEED STOCK AT A TEMPERATURE OF ABOUT 1100 TO 1200* F. AND A PRESSURE OF ABOUT 0 TO 300 P. S. I. GAUGE FOR ABOUT 1 TO 50 SECONDS IN THE PRESENCE OF HYDROGEN AND IN THE SUBSTANTIAL ABSENCE OF ANY CATALYTIC MATERIAL TO FORM A PRODUCT CONTAINING AN APPRECIATED AMOUNT OF AROMATIC HYDROCARBONS, COOLING SAID PRODUCT TO A TEMPERATURE OF NOT MORE THAN ABOUT 200* F. WITHIN ABOUT 30 SECONDS, DISTILLING SAID PRODUCT TO REMOVE HYDROCARBONS BOILING ABOVE AND BELOW THE BOILING RANGE OF SAID FEED STOCK AND RECOVERING A DISTILLED PRODUCT CONTAINING SAID APPRECIATED AMOUNT OF AROMATIC HYDROCARBONS. 